New species Dario urops is named in reference to the conspicuous ocellus on the caudal peduncle, the presence of which distinguishes it from the other three members of the genus, and it can be further told apart by presence of a horizontal suborbital stripe (vs. absence in congeners), by lacking extended lappets on the dorsal-fin spines (vs. possessing), and unusual vertebral counts (14+14–15= 28–29 vs 11–13+12–14=24–27).

It can also be told apart from D. dario and D. hysginonby lacking a dark stripe on the anterior margin of the pelvic-fin, and from D. dario by lacking vertical bars on the flanks in males.

The new species was first collected by British ichthyologist Francis Day more than 130 years ago at an unspecified locality in Wayanad district, Kerala state, and although he mentioned the presence of ‘B. dario‘ in the Western Ghats mountains in his works on Indian fishes these details were apparently overlooked by subsequent authors.

However, live specimens were recently collected at a single locality in southern Karnataka state, which borders Wayanad, and these were found to be conspecific with two lots of Day’s material housed at the Natural History Museum, London.

All other Dario spp. are native to the Brahmaputra and Ayeyarwaddy river systems in northern India, Myanmar, and southwestern China, meaning the discovery of a species in southern India greatly extends the known distribution of both the genus and family Badidae.

In addition, D. urops lacks some diagnostic characters of Dario as per Kullander and Britz (2002) and thus may represent the sister group of other members of the genus, though this hypothesis remains to be tested.

For further information see the full paper: Britz, R., A. Ali, and S. Philip, 2012. Dario urops, a new species of badid fish from the Western Ghats, southern India (Teleostei: Percomorpha: Badidae). Zootaxa 3348: 63-68. The abstract is available here.